In conventional oil and gas production processes, it is common to install a subsea tree structure on a well. The subsea tree structure is a piece of oilfield equipment which is in seated relationship to the well The tree structure will have a large number of valves and controls thereon so as to suitably facilitate the removal of oil and/or gas from the well. The installation of the subsea tree or other structures can be either diverless or diver assist. Once the subsea tree structure is installed, it must be connected for remote actuation so that proper controls can be maintained over the operation of the tree structure for the production of oil or gas from the well.
In conventional operations, an umbilical cable is interconnected to a fixed junction plate on the subsea tree structure. The umbilical cable extends from the tree structure to a production control skid mounted on an offshore platform or elsewhere above sea level. Typically, the subsea tree structure will include a large number of hydraulically-actuated valves. The umbilical cable is designed so as to allow for the delivery of hydraulic and/or electrical power to the subsea structure so that the fluids can properly operate the valves within the subsea tree structure. In normal operations, the umbilical cable is laid in the vicinity of a subsea structure by a barge or other device. The diver will then join the umbilical cable to the fixed junction plate on the subsea structure. In the case of a diverless connection, an R.O.V. or running tools are used to make this connection. Typically, the umbilical cable will extend for a great distance from the subsea structure or the manifold structure.
Presently, a junction plate is used so as to join the umbilical cable to the fixed junction plate of the subsea structure. Usually, the joining of these plates together is a cumbersome and time-consuming task for divers. It is essential to the operation of the subsea structure that the junction plates be joined properly. Therefore, in order to assure a proper joining of the junction plates, various complex devices have been employed, in the past, so as to assure a proper fit between the connections of the subsea structure and the connections within the junction plate.
Commonly, swing bolts are used so as to join the plates together. Swing bolts extend down over the plates and require a mechanical joining of the plates together. However, it is inherent in the nature of swing bolts that a deflection is created between the junction plate and the subsea tree structure. Whenever a deflection between the plates occurs, the poppet valves within the junction plates and within the subsea tree structure will tend to close. Poppets are arranged so as to close upon separation of the removable or fixed junction plates. Quick connect junction plates that require an over-center technique for locking must be precisely used so as to avoid such separation and such poppet closure.
Additionally, devices that have employed bolts and threaded members for the joining of the junction plates have been subject to the problem of galling. This problem of galling is particularly troublesome when stainless steel is used for the locking mechanism. Whenever the bolts are placed onto threaded members, a galling action has a tendency to occur. This is especially pronounced when the threaded members have conventional threads. Often, the threads are damaged during the installation process. This requires further efforts to correct the problem. These efforts can be very complex since they must proceed under water.
In existing diver-assist systems, it is necessary for the diver to carry a number of tools so as to properly install the junction plates together. Whether a swing bolt is used or nuts and bolts are used, the diver typically requires a wrench. This creates a complicated process of installation since the diver must secure the junction plate with one hand while attempting to manipulate the nuts and bolts with a wrench. Since the removable junction plate is a heavy item, this can be a particularly difficult task for the diver.
Another common problem t hat has been faced with prior art systems of joining the junction plates together has been the potentially damaging effects of exposing the sensitive hydraulic connections to the floor of the body of water. Many times, dirt, rocks, and other contaminants will enter into the hydraulic connections. It is often necessary for divers to remove any such particulate contamination from the hydraulic and/or electrical connections prior to installing the junction plate to the subsea structure. Instances have occurred in the past in which particulate matter has fouled the operation of the subsea structure. It is therefore very important that the hydraulic connections within the junction plates be kept free of contaminating material.
It is an object of the present invention to provide a junction plate assembly that assures a proper connection.
It is another object of the present invention to provide a junction plate assembly which is diver/ROV friendly.
It is a further object of the present invention to provide a junction plate assembly which minimizes risk of damage during installation.
It is still a further object of the present invention to provide a junction plate assembly that generally prevents particle intrusion into the connections of the junction plates.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.